Carbon dioxide (CO2) is considered an abundant and renewable C1 source, thus transition-metal mediated activation of this thermodynamically and kinetically stable molecule has received much attention over the last decade.1 In this context, C—C bond formation reactions simply involving CO2 and a unique metal center with allyl halides, alkenes, alkynes and allenes have been achieved, although with limited functional group compatibility.2-4,5 
In addition transition-metal mediated carbonylation of heterocyclic N—H and C—H bonds represents a nascent area in organic chemistry, enabling efficient construction of valuable synthons.1 Palladium-catalysed N-carbonylation is well-documented, but requires high catalyst loading and the utility of either gaseous carbon monoxide or Group VI metal-carbonyl complexes.2 This transformation is also promoted by molybdenum and tungsten carbonyl amine species under forcing temperatures.3 Several successful approaches to C-carbonylation have been reported using ruthenium1a and nickel catalysts,4 however examples under mild conditions remain elusive. Moreover, substrate scope is limited to arenes that are either electron-rich or bear synthetically restricting directing groups, and the product is often recovered as a regioisomeric mixture.
There is therefore a need to find alternative means of adding carbon as a C1 unit to a substrate in synthetic chemistry, for example in the form of CO2.